Segment sensitive scheduling

• US 9,240,877 B2
• Filed: 02/18/2009
• Issued: 01/19/2016
• Est. Priority Date: 08/22/2005
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Gorokhov, Alexei Y., Ji, Tingfang
• Primary Examiner(s): Shah, Chirag
• Assistant Examiner(s): REDDIVALAM, SRINIVASA R
• Application Number:
  US12/372,954
• Publication Number:
  US 20090201872A1
• Time in Patent Office: 2,526 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: H04L 1/0002 by adapting the transmission rate
• CPC Class Codes: H04L 1/0009 by adapting the channel coding H04L1/1812 takes precedence
• CPC Class Codes: H04L 1/0026 Transmission of channel quality indication
• CPC Class Codes: H04L 1/1812 Hybrid protocols; Hybrid automatic repeat request [HARQ]
• CPC Class Codes: H04L 25/0398 Restoration of channel reciprocity
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04L 5/0044 allocation of payload
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver
• CPC Class Codes: H04L 5/0057 Physical resource allocation for CQI
• CPC Class Codes: H04L 5/006 Quality of the received signal, e.g. BER, SNR, water filling
• CPC Class Codes: H04L 5/0064 Rate requirement of the data, e.g. scalable bandwidth, data priority
• CPC Class Codes: H04L 5/1438 Negotiation of transmission parameters prior to communication modified according to link quality H04L1/0001

Abstract

Systems and methods of scheduling sub-carriers in an OFDMA system in which a scheduler takes into account channel conditions experienced by the communication devices to optimize channel conditions. The scheduler can partition a set of sub-carriers spanning an operating bandwidth into a plurality of segments. The segments can include a plurality of global segments that each includes a distinct non-contiguous subset of the sub-carriers spanning substantially the entire operating bandwidth. One or more of the global segments can be further partitioned into a plurality of local segments that each has a bandwidth that is less than a channel coherence bandwidth. The scheduler determines channel characteristics experienced by each communication device via reporting or channel estimation, and allocates one or more segments to communication links for each device according to the channel characteristics.

Claims

1. An apparatus for channel sensitive scheduling in a communication system including a plurality of sub-carriers spanning an operating frequency band, the apparatus comprising:

a channel estimator executably configured to determine a channel estimate corresponding to each of a plurality of segments spanning the operating frequency band based on pilot signals, each of the plurality of segments having a bandwidth less than a total bandwidth;

a signal mapper executably configured to map data symbols to a subset of the plurality of sub-carriers in the communication system;

a scheduler coupled to the channel estimator and executably configured to determine a first preferred segment based on the channel estimates and user data constraints of data to be transmitted, determine a number of sub-carriers assigned to the subset of the plurality of subcarriers based on one or more signal conditions, select the subset of the plurality of sub-carriers from within the first preferred segment, and further executably configured to control the signal mapper to map the data symbols to the subset of the plurality of sub-carriers; and

a Channel Quality Indicator (CQI) receiver coupled to a receiver module and executably configured to process channel characteristic reporting messages received by the receiver module to determine a second preferred segment and further configured to generate a resource assignment message based on the channel characteristic reporting messages.

2. The apparatus of claim 1, wherein the receiver module is executably configured to receive reverse link pilot signals and wherein the scheduler is executably configured to select the subset of the plurality of sub-carriers for a forward link transmission based on the reverse link pilot signals.

3. The apparatus of claim 1, wherein the pilot signals comprise reverse link pilot signals and the scheduler is executably configured to generate a reverse link resource assignment message for transmission to a user terminal based on the channel estimates.

4. The apparatus of claim 1, wherein the scheduler is executably configured to select the first preferred segment as a segment having a largest signal to noise ratio determined from the pilot signals.

5. The apparatus of claim 1, further comprising a frequency hopper module executably configured to enforce a frequency hopping scheme within the first preferred segment.

6. A method for channel sensitive scheduling in a communication system including a plurality of sub-carriers spanning an operating frequency band, the method comprising:

determining a channel estimate corresponding to each of a plurality of segments spanning the operating frequency band based on pilot signals, each of the plurality of segments having a bandwidth less than a total bandwidth;

mapping data symbols to a subset of the plurality of sub-carriers in the communication system;

determining a first preferred segment based on the channel estimates and user data constraints of data to be transmitted;

determining a number of sub-carriers assigned to the subset of the plurality of subcarriers based on one or more signal conditions;

selecting the subset of the plurality of sub-carriers from within the first preferred segment;

mapping the data symbols to the subset of the plurality of sub-carriers;

and

processing channel characteristic reporting messages received by a Channel Quality Indicator (CQI) receiver coupled to a receiver module to determine a second preferred segment and further comprising generating a resource assignment message based on the channel characteristic reporting messages.

7. The method of claim 6, further comprising receiving reverse link pilot signals and selecting the subset of the plurality of sub-carriers for a forward link transmission based on the reverse link pilot signals.

8. The method of claim 6, wherein the pilot signals comprise reverse link pilot signals and generating a reverse link resource assignment message for transmission to a user terminal based on the channel estimates.

9. The method of claim 6, further comprising selecting the first preferred segment as a segment having a largest signal to noise ratio determined from the pilot signals.

10. The method of claim 6, further comprising enforcing a frequency hopping scheme within the first preferred segment.

11. A non-transitory computer-readable tangible medium including computer-executable instructions for executing a method for channel sensitive scheduling in a communication system including a plurality of sub-carriers spanning an operating frequency band, the method comprising:

determining a channel estimate corresponding to each of a plurality of segments spanning the operating frequency band based on pilot signals, each of the plurality of segments having a bandwidth less than a total bandwidth;

mapping data symbols to a subset of the plurality of sub-carriers in the communication system;

determining a first preferred segment based on the channel estimates and user data constraints of data to be transmitted;

determining a number of sub-carriers assigned to the subset of the plurality of sub-carriers based on one or more signal conditions;

selecting the subset of the plurality of sub-carriers from within the first preferred segment;

mapping the data symbols to the subset of the plurality of sub-carriers; and

processing channel characteristic reporting messages received by a Channel Quality Indicator (CQI) receiver coupled to a receiver module to determine a second preferred segment and further comprising generating a resource assignment message based on the channel characteristic reporting messages.

12. The non-transitory computer-readable tangible medium of claim 11, the method further comprising receiving reverse link pilot signals and selecting the subset of the plurality of sub-carriers for a forward link transmission based on the reverse link pilot signals.

13. The non-transitory computer-readable tangible medium of claim 11, wherein the pilot signals comprise reverse link pilot signals and the method further comprising generating a reverse link resource assignment message for transmission to a user terminal based on the channel estimates.

14. The non-transitory computer-readable tangible medium of claim 11, the method further comprising selecting the first preferred segment as a segment having a largest signal to noise ratio determined from the pilot signals.

15. The non-transitory computer-readable tangible medium of claim 11, the method further comprising enforcing a frequency hopping scheme within the first preferred segment.

16. An apparatus for channel sensitive scheduling in a communication system including a plurality of sub-carriers spanning an operating frequency band, the apparatus comprising:

means for determining a channel estimate corresponding to each of a plurality of segments spanning the operating frequency band based on pilot signals, each of the plurality of segments having a bandwidth less than a total bandwidth;

means for mapping data symbols to a subset of the plurality of sub-carriers in the communication system;

means for determining a first preferred segment based on the channel estimates and user data constraints of data to be transmitted;

means for determining a number of sub-carriers assigned to the subset of the plurality of sub-carriers based on one or more signal conditions;

means for selecting the subset of the plurality of sub-carriers from within the first preferred segment;

means for mapping the data symbols to the subset of the plurality of sub-carriers; and

means for processing channel characteristic reporting messages received by a Channel Quality Indicator (CQI) receiver coupled to a receiver module to determine a second preferred segment and further comprising means for generating a resource assignment message based on the channel characteristic reporting messages.

17. The apparatus of claim 16, further comprising means for receiving reverse link pilot signals and means for selecting the subset of the plurality of sub-carriers for a forward link transmission based on the reverse link pilot signals.

18. The apparatus of claim 16, wherein the pilot signals comprise reverse link pilot signals and the apparatus further comprises a means for generating a reverse link resource assignment message for transmission to a user terminal based on the channel estimates.